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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Combined Influence of Size and Sonication on Constant Shear Viscosity of MgO-Ethylene Glycol Nanofluids

Get access (open in a dialog) DOI: 10.1615/IHTC15.tpp.008606
pages 8927-8938

Resumo

Nanofluids prepared from the combination of MgO and Ethylene glycol have been shown to have high thermal conductivity, higher than those from Al2O3, but almost no attention has been given to this nanofluid with regard to its rheological behavior. In order to understand the suitability of this fluid in equipment and devices such as heat exchangers, micro-channels, heat pipes etc., its viscosity needs to be investigated. Therefore, this paper presents the result of experiments on three different sizes (20, 40 and 100 nm) of MgO nanofluids sonicated for 30 min and 60 min respectively. The experiments were carried out for volume fraction in the Einstein concentration regime (up to 2% volume fraction of MgO). From the present experimental data, MgO-Ethylene glycol nanofluids respond exponentially to change in temperature as the temperature was increased from 20 – 70 °C. Likewise increase in volume fraction shows a corresponding increase in the viscosity, however, the 20 nm MgO nanoparticle shows higher viscosity in ethylene glycol nanofluids compared to other sizes investigated. The TEM imagery suggests that 40 nm and 100 nm MgO nanoparticles are averagely 86 and 110 nm respectively. This informed the close proximity of the results of the nanofluids samples formulated from these two sizes. The relative viscosity was compared with some existing classical and empirical models, especially for those developed for the volume fraction regime investigated in this paper. Lastly, it was found than excess sonication energy leads to breakage of 100 nm particles leading to a slight increase in the relative viscosity.